This critter "on the half-shell" shows some of the internal anatomy
of a brachiopod quite well. First note the two valves or shells. All
brachiopods have two shells. This makes brachiopods look superficially
like bivalved molluscs (clams, oysters, etc.) However, a closer inspection
shows some striking differences. Note that each shell valve is symmetrical
about the midline, but the two shell valves are often unequal in size. This
is unlike most clams, which have two equal valves, each of which is slightly
torted and thus asymmetrical across the midline.

(Unfortunately, the source of this image is unknown
to us. It is probably not derived from UCMP. If you know the source, please
let us
know.)

Notice the typical brachiopod feeding structure, the
lophophore
curled up on the right side. The rest of the anatomy is easier seen in this
schematic cross-section of a brachiopod.